Within the
sensory nervous system
The sensory nervous system is a part of the nervous system responsible for processing sensory information. A sensory system consists of sensory neurons (including the sensory receptor cells), neural pathways, and parts of the brain involved i ...
, Secondary sensory endings of the
muscle spindle
Muscle spindles are stretch receptors within the body of a skeletal muscle that primarily detect changes in the length of the muscle. They convey length information to the central nervous system via afferent nerve fibers. This information can be ...
are composed of
type II sensory fiber
Type II sensory fiber (group Aβ) is a type of sensory fiber, the second of the two main groups of touch receptors. The responses of different type Aβ fibers to these stimuli can be subdivided based on their adaptation properties, traditionall ...
s that terminate on
nuclear chain fiber
A nuclear chain fiber is a specialized sensory organ contained within a muscle. Nuclear chain fibers are intrafusal fibers that, along with nuclear bag fibers, make up the muscle spindle responsible for the detection of changes in muscle length ...
s and static
nuclear bag fiber
A nuclear bag fiber is a type of intrafusal muscle fiber that lies in the center of a muscle spindle. Each has many nuclei concentrated in bags and they cause excitation of the primary sensory fibers.
There are two kinds of bag fibers based up ...
s, but not dynamic nuclear bag fibers. Whereas primary endings respond mostly to rate of change, secondary endings respond mostly to amount of stretch.
[McEachron, Donald. "Spinal Lecture Part 1." Drexel University, 2012 of School of Biomedical Engineering, Science, and Health Systems]
References
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Sensory systems